The present invention relates to a novel vinylsilyl group-containing polymeric compound having a monodisperse distribution of the molecular weight and a method for the preparation thereof. More particularly, the invention relates to a vinylsilyl group-containing monodisperse polymeric compound having curability by irradiation with actinic rays and useful as a negative-type photoresist material and a method for the preparation thereof.
In the electronic technology of recent years, a variety of semiconductor devices are being manufactured by the precision photolithographic techniques using a photoresist material which may be of the negative type or positive type. Along with the progress of the electronic technology, the demand for the fine working is increasing more and more reaching the precision of so-called submicron range and the photoresist material is also required to have a high sensitivity and high resolving power.
As is known, the use of a negative type polymeric photoresist material constitutes the major current of the above mentioned photolithographic techniques in the electronic industry in comparison with positive type ones. The negative type photoresist material should satisfy various requirements to be practically usable including: (1) that the photoresist material has a high sensitivity to crosslink formation when irradiated with actinic rays such as ultraviolet light, far ultraviolet light, electron beams, X-rays and the like; (2) that substantial changes should be produced in the molecular structure and properties before and after the irradiation with actinic rays such as a difference in the solubility parameter as large as possible caused by the crosslink formation; (3) that the polymeric material has an adequate molecular weight and the molecular weight distribution should be as narrow as possible; i.e. monodisperse, if possible, in order to obtain increased sensitivity and resolving power; (4) that the glass transition temperature T.sub.g should be relatively high; (5) that the layer of the photoresist composition should have good adhesion to the surface of the substrate on which it is formed; and (6) that the photoresist layer after patterning should have a high resistance against dry etching.
Of the currently used negative type photoresist materials, the most widely used are those based on a cyclized rubber but none of the photoresist materials available on the market satisfies all of the above described requirements simultaneously so that it is eagerly desired in the technology of electronics to develop a negative type polymeric photoresist material capable of satisfying these requirements.